This invention relates to latch assemblies for the access door on a video tape cassette of the type used in a video recording and playback machine, such as the "U-Matic" cassette developed by Sony Corporation and described in U.S. Pat. No. 3,740,495.
As is illustrated in FIGS. 1 and 2 of the drawing, a prior art video tape cassette 10 typically comprises a length 11 of magnetizable recording tape, two reels 12 each supporting a different helically wound end portion of the length 11 of tape, and a generally rectangular housing 14 enclosing and supporting the reels 12 for rotation to transfer tape between the reels 12. The housing 14 includes an outer front wall having a generally planar end portion 16, a recessed portion 18 defining a tape access area along the outer surface of the housing 14, and means for guiding tape between the reels 12 through the outer wall and across the recessed portion 18 to afford access thereto by the mechanism of a video tape recording/playback machine. A door 20 is pivotably mounted on the housing 14 via a hinge 21 for movement between a closed position over tape extending through the tape access area (to which closed position the door 20 is biased by a spring 22) and an open position spaced from the tape access area.
A latch assembly (FIG. 2) releasably retains the door 20 in its closed position. The latch assembly comprises a channel 24 defined by an L-shaped protrusion located on the edge of the door 20 opposite the hinge 21 and adjacent the planar end portion 16, and a movable member (such as the movable member 26 shown in FIG. 2) mounted on the housing 14 for movement between an engaged position to which the movable member is biased and a disengaged position to correspondingly move the movable member in or out of engagement with the channel 24 when the door 20 is in its closed position. The movable member has a cam surface (such as the surface 30 shown in FIG. 2) adapted for engagement by a projection on a recording/playback machine through an access opening 32 in the planar end portion 16 to move the member to its disengaged position so that the access door can be opened by the machine into which the cassette 10 is inserted.
In one prior art cassette described in U.S. Pat. No. 3,873,045 the movable member is a lever pivotably mounted on the housing, whereas in the prior art cassette illustrated in FIG. 2 (which is believed to be the closest prior art to the present invention), the movable member 26 is slidably mounted in the housing 14 and includes a projection 27 adapted to engage the channel 24. Both of these prior art latch assemblies include a separable metal wire coil spring (such as the spring 34 shown in FIG. 2) to bias them to their engaged position, resulting in a latch assembly which requires assembly time to position the spring between the movable member and the housing, and which is more costly to produce than might otherwise be desired.